For sulfonating



Patented July 22, 1952 It has been found high molecular weight, which as free acids, or in. the form of their alkali metal salts give a clear solution in water, are produced when -;poly

styrol, preferably in the presence ofsolvents, is

treated with addition compounds ,of sulphuric anhydride on organicsubstance's; ,.=As components for such addition compounds acyclic ethers are particularly suitable, such as dioxane and thioxane. As solvents it is preferable to employ chlorinated aliphatic hydrocarbons, such for example as carbon tetrachloride, ethylene,- dichloride, or ethane tetrachloride.

The product of polystyrol sulphonic acids by the action oi. sulphonating means, such as sulphuric acid, oleum and chlorosulphonic acid, upon polystyrol is known. The polystyrol sulphonic acids produced by this process do not give a clear solution in water, either as free acids or in the form of their alkali metal salts. They swell considerably in water. Suspensions of the swollen substances in water cannotbe filtered. Very coarse filters with pores of the size of 200 are 'quickly choked completely by the gel 'lumps. From very dilute solutions after standing for a long time, the swollen particles of the polystyrol sulphonic acids or their salts settle as voluminous precipitates. For many purposes this is a great disadvantage, and it is therefore of particular importance that by the process according to the present invention, polystyrol, sulphonic acids are obtained which give clear solutions in water as free acids or as alkali metal salts. The aqueous solutions of the acids and of the alkali metal salts can be filtered through fine filters with a size of pore of 20 without any choking of the filter. in water does not take place even after long standing.

The difference in the properties of the polystyrol sulphonic acids obtained by the known processes and those obtained by the new process according to the invention is to be explained by the fact that according to the known process. when sulphonating, not only sulphonic acid groups but also sulphogroups are obtained, which "knit the polystyrols together and therefore give rise only to compounds capable of swelling in water but not to compounds giving a clear solution in water.

The production of sulphonic acids by thetreatment of aromatic hydrocarbons of low molecular weight with the addition product of sulphuric anhydride on dioxane is already known. It was however by no means to be expected, and is in- A deposition. of the particles dissolved .fiR'ooEss FOR SULFONATING- I 1T -P OLYSTYRENE that sulphonic acids-of deed very surprising, that position products'clearly soluble inwater are ob tained only when sulphonation-is efiecte d with addition compoundsqof sulphuric anhydride on organic compounds such as-.;dioxane or; :thioxane:

The new sulphonic acids i: high 5 molecular Weight are very good protective colloids,;,and; can

be easily; obtainedeven. in large-quantities a colourlessflforms Theymay be employed-resid stance for improvingthe prqpfirtiesoi detergents,- for the fine; distribution of dyestufis orgermi cides in water, or for theqproduction; of dressings and of leather dyes.';{If:i.polystyrol1pf, particularly high molecular .weight is employed, sulphonic acidsare obtained of which the alkali metal salts are very suitableflfor the production of thickening'agents for printing on clothfl" e 1 w V w re Into a mixtureoi ll parts by weight of dioxane and 40 parts by volumeoi' carbon tetrachloride are slowly introduced .with cooling, IOparts by weight of sulphuri anhydride. l There; lis then formed, with greatlevolutionrof he ridp'fecim itated, the addition compound of 1 incl: $03 to 1' mol dioxane. To this mixture 15 parts by weight of polystyrol dissolved in 40 parts by volume of carbon tetrachloride are added, and are thoroughly mixed at room temperature for some hours. After the addition of water the mixture is separated by centrifuging into two layers. The lower layer, consisting of the carbon tetrachloride and part of the dioxane employed, is drawn off. The aqueous layer contains the polystyrol sulphonic acid, which is evaporated to dryness either directly or after conversion into the sodium salt by the addition of soda lye.

The free sulphonic acid and the sodium salt give a clear solution in water. The aqueous solutions are viscous and colourless.

Instead of dioxane, thioxane maybe employed with the same result.

Example 2 with polystyrol,

cous colourless solution remaining behind is evaporated. The sodium salt of a polystyrol sulphonic acid which gives a solution in wateris obtained.

With this example also, thioxane maygbeemployed in place of dioxane.

Example 3 Into a mixture of 9 parts by weight oi dioxane; and 40 parts by weight of ethylene dichloride are} introduced 6.9 parts byweight of sulphuric an- 10 4. A process'for the production of polystyrolsulphonic acids which give a clear solution in hydride, with cooling. To this mixture are added 45 Parts by Weight 0f yrol dissolved in 150" ing thoroughly mi'xedtogether for 6 hours.

The reaction'mixture is treated with the, same volume'of methanol and,.;mechanically mixed, a

v homogeneous solution being obtained. In a vacuum of 15 mm. at atemp'erature of 40C. the organic solvents are distilled ofi from this'solution, the same volume of water being at'the same time added by drops, so that after the termination of the distillation an aqueous solution "of a polystyrol containing a'fewsulphonic acid groups is obtained. This is neutralized with lye'when a'n 7 aqueous solution of the salt isneeded. The aqueous solutions of these low sulphonated'acids andsalts have the property of separating the dissolved material, after evaporation and drying, in a form whi'ch'is insoluble in water."

The same compounds are obtained if thioxane is employed instead of, dioxane. 1

Iclaism:- LA process'ior the production of polystyrol sulphonic acids which give a clear solution in water as alkali metal salts, consisting in treating polystyrol, at approximately room temperature, with addition compounds of sulphuric anhydride on cyclic ethers of the group consisting of dioxane andthioxane. i

2. AYPTOQESS tor the production-of polystyrol sulphonic aoids which give a clearsolution in water as alkali'metal salts, consisting in treating polystyrol, at approximately room temperature, with the addition product of sulphuric anhydride on dioxane.

3. A process for the production of polystyrol sulphonic acids which give a clear solution in water as alkali metal salts, consisting in treating ,.poly'styro1',' at approxini{atelyi room temperature, with the addition product of sulphuric anhydride on thioxane.

water as alkali metal salts, consisting in carrying out the reactionvof the polystyrol with an additio'n compound ofsulphuric anhydride on a cyclic ether of the group consisting of dioxane parts by weight of ethylene .dichloridethese be, u-ialiphatic 'g-hydrocarbon as solvent,

action being carried out at approximately room 20 and-,thioxanein-the presence of a chlorinated REFERENCES CITED The following references are of record in the file of this patent: V

UNITED STATES PATENTS Number Name Date 7 2,533,211 Baer Dec. 12, 1950 j FOREIGN PATENTS Number Country I r Date 580,366 Germany July 13, 1933 OI'IIHEBREFERENCES j Suterz J. Chem. Soc 60, 538-40 (1938).

said re-. 

1. A PROCESS FOR THE PRODUCTION OF POLYSTYROL SULPHONIC ACIDS WHICH GIVE A CLEAR SOLUTION IN WATER AS ALKALI METAL SALTS, CONSISTING IN TREATING POLYSTYROL, AT APPROXIMATELY ROOM TEMPERATURE, WITH ADDITION COMPOUNDS OF SULPHURIC ANHYDRIDE ON CYCLIC ETHERS OF THE GROUP CONSISTING OF DIOXANE AND THIOXANE. 